Single pass 7 watts continuous wave 532 nm generation by focusing optimized second harmonic generation in MgO:PPLN

Thermal effect in high-power CW single-pass 1064 nm SHG for 532 nm generation using MgO:PPLN crystal has been theoretically and experimentally investigated. By careful control of the focusing condition to deal with the well-known thermal issue such as thermal lensing and dephasing in MgO:PPLN crystal, we have successfully generated >7W green output at 532nm using a 25mm long crystal without observing optical damage. This achievement has enhanced the maximum CW green power generated through MgO:PPLN crystal by a factor of 3 as compared to the common optimization under low power condition, and by a factor of 2 as compared to the scheme of single-pass multi-crystal cascading SHG. To our best knowledge, this result gives the highest CW green power via SHG of MgO:PPLN crystal. Furthermore, a systematic study for SHG optimization has shown that >30% SHG conversion efficiency can be achieved from 2W to 7W under output-power dependent optimization.